The patch titled
Subject: exec: use force_uaccess_begin during exec and exit
has been added to the -mm tree. Its filename is
exec-use-force_uaccess_begin-during-exec-and-exit.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/exec-use-force_uaccess_begin-during-exec-and-exit.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/exec-use-force_uaccess_begin-during-exec-and-exit.patch
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------------------------------------------------------
From: Christoph Hellwig <hch@xxxxxx>
Subject: exec: use force_uaccess_begin during exec and exit
Both exec and exit want to ensure that the uaccess routines actually do
access user pointers. Use the newly added force_uaccess_begin helper
instead of an open coded set_fs for that to prepare for kernel builds
where set_fs() does not exist.
Link: http://lkml.kernel.org/r/20200710135706.537715-7-hch@xxxxxx
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Acked-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Nick Hu <nickhu@xxxxxxxxxxxxx>
Cc: Greentime Hu <green.hu@xxxxxxxxx>
Cc: Vincent Chen <deanbo422@xxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/exec.c | 7 ++++++-
kernel/exit.c | 2 +-
2 files changed, 7 insertions(+), 2 deletions(-)
--- a/fs/exec.c~exec-use-force_uaccess_begin-during-exec-and-exit
+++ a/fs/exec.c
@@ -1380,7 +1380,12 @@ int begin_new_exec(struct linux_binprm *
if (retval)
goto out_unlock;
- set_fs(USER_DS);
+ /*
+ * Ensure that the uaccess routines can actually operate on userspace
+ * pointers:
+ */
+ force_uaccess_begin();
+
me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
PF_NOFREEZE | PF_NO_SETAFFINITY);
flush_thread();
--- a/kernel/exit.c~exec-use-force_uaccess_begin-during-exec-and-exit
+++ a/kernel/exit.c
@@ -731,7 +731,7 @@ void __noreturn do_exit(long code)
* mm_release()->clear_child_tid() from writing to a user-controlled
* kernel address.
*/
- set_fs(USER_DS);
+ force_uaccess_begin();
if (unlikely(in_atomic())) {
pr_info("note: %s[%d] exited with preempt_count %d\n",
_
Patches currently in -mm which might be from hch@xxxxxx are
syscalls-use-uaccess_kernel-in-addr_limit_user_check.patch
nds32-use-uaccess_kernel-in-show_regs.patch
riscv-include-asm-pgtableh-in-asm-uaccessh.patch
uaccess-remove-segment_eq.patch
uaccess-add-force_uaccess_beginend-helpers.patch
exec-use-force_uaccess_begin-during-exec-and-exit.patch
